In the cold mists of the Antarctican wastes, beyond the dreaded dead city of Leng lies that which even the Old Ones were held fast in reverence. The evil which lurks there may never be spoken of, even the mad Abdul Alhazred dared not even allude to in the Necronomicon. Neither man nor fiend darest mount it slopes; and for all of the ancient and eldritch horrors of the Cthulhu spawn, the Mi-Go, and the Fungi from Yuggoth, A Colour out of space shed not even the dimmest light of the unspoken darkness of that is the towering mountain realm of Kadath.
wrote in one of his assorted letters that the horror witnessed by Danforth (in "At the Mountains of Madness
") within the visage of the Shoggoth was something much more hideous then the Old Ones
... he mentioned that the greatest evil; that is, the very rotten core of the Earth
, lies up in the Kadath, beyond the cold wastes. He writes that he would like to write a sequel to At the Mountains of Madness
- a journey to the mountain Kadath. He died very young, however, so we will never know what HP imagined to be the ultimate darkness gripping the Earth. Lamentable
, for sure...